firmware: remove warning at documentation generation time

This patch removes following error at for `make htmldocs`. No functional
change.

	./drivers/base/firmware_class.c:1348: WARNING: Bullet list ends without a blank line; unexpected unindent.

Signed-off-by: Silvio Fricke <silvio.fricke@gmail.com>
Reviewed-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Acked-by: Luis R. Rodriguez <mcgrof@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/base/firmware_class.c

@@ -1384,9 +1384,9 @@ static void request_firmware_work_func(struct work_struct *work)
  *
  *	Asynchronous variant of request_firmware() for user contexts:
  *		- sleep for as small periods as possible since it may
- *		increase kernel boot time of built-in device drivers
- *		requesting firmware in their ->probe() methods, if
- *		@gfp is GFP_KERNEL.
+ *		  increase kernel boot time of built-in device drivers
+ *		  requesting firmware in their ->probe() methods, if
+ *		  @gfp is GFP_KERNEL.
  *
  *		- can't sleep at all if @gfp is GFP_ATOMIC.
  **/